Process of preparing lactoflavin concentrates



Dec. 13, 1938. H. F. SEIBERT PROCESS OF PRPARING LACTOFLAVIN CONCENTRATES Filed March 29, 1957 MP4 mPZmU ZOU JNVENTGR HOWARD F. sElBERr mmumn. mmPJ-u Patented Dee. 13, 193s UNITED STATES aisass'z PROCESS 0F PBEPARING LACTGFIAVIN CONCENTRATES Howard r. Seibert, cleveland, ohio, assignor, by mesne assignments, to S. M. A. Corporation, Jersey City, N. J., a. corporation ot New Jersey Application March 29, 1937, Serial No. 133,503

10 Claims.

My invention relates to animproved method ofv preparing lactoilavin concentrates. More particularly, it relates to an improved method by means of which lactoiiavin concentrates may be produced in an economical manner without utilizing poisonous solvents.

As well known to those skilled in the art, lactoavin is a greenish-yellow uorescent pigment which, in aqueous solution, has a yellow to orange color possessing an active greenish uorescence. It occurs in the whey of milk and has recently become of considerable importance in the biological art because it has beenascertained that vitamin B2 is associated, to a partial extent at i5 least, with this pigment. Vitamin B2 is of con'- siderable importance in the ldiet because it preserves the nerve health, improves the'appetite, and aids the growth of children.

Heretofore, lactoavin concentrates have been v prepared by treating the whey of milk with fullers earth which acts as an adsorbent. The fullers earth was then eluted with a mixture o f pyridine-methanol and water and the solution was subsequently evaporated to provide the lactoiiavin concentrate. There are considerable objections to this method, however, because it is dimcult to remove the last traces of pyridine and methanol, both of which are poisonous solvents. 'Ihe yields obtained, were also very low and con- ;50 sequently the vcost of the concentrate has been exceedingly high.

In accordance with my invention, I have provided an improved process of preparinglactoavin concentrates in a simple manner by means 3 5'- of which theconcentrate may be prepared at a much'lower cost than by former methods and in which thev use o! poisonous solvents is entirely eliminated. v 'It is therefore an object oi' nLv invention to 40' vprovide an economical process of preparing lactofiavinconcentrates by means of which comparatively high yields are obtained. Y c Another object of my invention is to provide an improved process of preparing lactoiiavinconcentrates by means of which poisonous sol-v vents are eliminated and a lactofiavin concen-- position resulting from oxidation or irradiation.

trate obtained which may be utilized alone or in medicinal or food preparations.

I n accordance with my invention a lead salt is ilrst dissolved or partially dissolved and partially suspended in an'aqueous solution containl ing lactoflavin. As the solution containing thelactoilavinl may utilize the whey of milk or dissolve whey solids in water to form an aqueous so- QQ lution. Other solutions containing lactoilavin (C1.4 16v-s1) may also be employed, such as an aqueous solution of egg albumin or the aqueous extract of alfalfa meal or of animal or fish liver. I preferably utilize a metal salt which is soluble in water, such as the formates, acetates or propionates of 5 lead although inorganic salts,.such aschlorides or carbonates may be employed. In general it may be stated that any lead salt whichis soluble or partially soluble -in the solution containing the lactofiavin may be employed. Y1

Hydrogen t sulphide is then passed rapidly through the solution. vDuring the formation of the precipitate, the lactoflavin is adsorbed. In order to provide the best results the amount of lead salt which is added is just suiiicient or slight- '-ly in excess of the amount required to adsorb the lactoavin, when the precipitate is formed. 'Ihe amount of the lead salt to be added may be determined by taking test samples of the solution and determining by trial'and error the -20 amount of the precipitate which will adsorb the pigment. As the pigment is uorescent in ultraviolet light, this may be readily Adetermined by experiment. During the formation of the precipitate, iiuorometric tests may be made at de- :5 4sired intervals to determine whether all the pigment has been adsorbed. l

A lter aid,such as nely divided diatomaceous earth is then added to the solution which is illtered. The lter cake is next washed with cold water and 'is transferred to an eluting tank and a sufficient amount of water or ethyl alcohol, or a mixture of ethyl alcohol and water, is added to form a suspension oi the cake which is heated to the boiling point and-held at that temperature l3,3

for approximately five minutes. Water is preferred'as theeluting agent because lactoiiavin is much more soluble in water than in ethyl alcohol. The suspension is then illtered', the illtrate containing the eluted lactoavin. 'I'he lter v40 solidsy or cake is subjected several times to the same treatment and the combined filtrates are concentrated, preferably in a vacuum or ink an inert atmosphere to a convenient volume to form the desired concentrate. Better yields are obtained if precautions are taken to prevent decom- The material/however may be concentrated in the open air or under atmospheric conditions where ordinary precautions are takento prevent oxidad tion. The lead sulphide, during its precipitation, is superior to fullers earth, `carbon or other adsorbentsfbecause after precipitation, the lactoavln may be much more readily and 'completely removed from the lead sulphide than from other 'vents, such as methanol or pyridine, or nonpoisonoussolvents, such as water or ethyl alcohol, are employed as eluting agents because the. lactofiavin may be much more readily and completely eluted from the lead sulphide than-from other adsorbents, such as carbon or fullers earth.

It will also be understood that it is not essential that the water or the mixture of water and alcohol utilized in eluting the lactofiavin should be heated to the boiling point. For instance, the lactoavin may be eluted with water at ordinary temperatures. However, when water at such temperature is employed it requires a longer time to remove the lactoflavin. It is therefore desirable to heat the water to a temperature of at least 80" to 90 C. and preferably to the boiling point because at such temperatures the lactoavin may be readily eluted from the lead sulphide.

In my improved process it is essential to precipitate the metal salt Within a reasonable time. 'Ihe rate vwill vary somewhat under different conditions, but for best results it should be effected as quir"ly a. possible. If the precipitate isl formed too slowly, poor yields and ineffective adsorption ,occurs It is also essential that the formed precipitate should not be allowed to remain in the solution for an extended period of time because the lactofiavin has the tendency to redissolve It is therefore desirable in my improved process that the precipitation of the metal and the filtering of the cake should be accomplished as quickly as possible.

The following specific example will serve to illustrate and explain my improved process, although it will be understood that I do not desire to be limited to the specific proportions or details recited therein. Approximately 40 gallons of an aqueous solution containing 90 pounds of milk whey solids was first filtered and placed in a tank provided with a vented cover, an agitator and a glass lined or fused surface which is not chemically reactive toward hydrogen sulphide. About 3.5 pounds of lead acetate were added and hydrogen sulphide was then rapidly passed through the solution which reacts` with the lead acetate, forming a precipitate of lead sulphide. In order to expedite the reaction between the hydrogen sulphide and the lead acetate, it is desirable to introduce the hydrogen sulphide into the bottom of the solution in such a manner that the gas will be rapidly disseminated through the solution. For instance the hydrogen-sulphide may be introduced into the solu-` tion through a perforated copper ring or coil at the bottom of the tank connected to a lead in pipe communicating with the hydrogen supply tank. The solution is also preferably agitated during theintroduction of the hydrogen sulphide. As the lead sulphide precipitates, the lactoflavin is adsorbed, until at the end of about one to two hours practically all the lactoflavin is adsorbed. A filter aid consisting of finely divided diatomaceous earth is then added and the solution filtered.

The solidv. precipitate or cake, thus prepared,

' the was washed with .approximately 5 gallons of cold water and the cake was transferred to a elution tank provided with a steam jacket., Approximately- 3 gallons of hot water was then added to lter cake to form a suspension, the temperature of which was raised to the boiling point and held at that temperature for approximately v ve minutes, after which the mixture was ltered or lcentrifuged to remove the cake; The cake was again returned to the elution tank and suspended in approximately 3 gallons of water which was heated to the boiling point and held at that temperature for approximately five min- -utes. 'Ihe suspension was again filtered or centrifuged, the cake being returned to the elution tank for another similar treatment. The combined ltrates containing the lactofiavin were then concentrated under vacuum until the concentrate was reduced to the desired volume.

The accompanying flow sheet illustrates the lsteps utilized in my improved process. In the drawing, the numeral i designates a tank containing the lactoiiavin solution, the numeral 2 designates the precipitation tank, 3 a suitable filter press, the elution tank, 6 a lter, 6 a storage tank, and 'i the vacuum pans.

In practicing my improved process it is highly desirable to provide means for precipitating the lead sulphide rapidly. The rate maybe varied somewhat under different conditions but apparently it cannot be conducted too quickly.

On the other hand, if the precipitation is conducted'too slowly the adsorption is inefcient and poor yields are obtained. It is also desirable that the precipitated lead sulphide containing the '.dsorbed lactoflavln should be filtered promptly after precipitation, otherwire the lactoilavin begins to go back into solution and after a period of from five to six hours completely returns to solution. It is therefore essential to filter the precipitate promptly in order to obtain the best yields and for successful practice the precipitate should be filtered within a period of from one to two hours.

The particular reason why the lead sulphide adsorbs lactoavin during its precipitation is not definitely understood. It is believed, however, that its effectiveness is due tothe fact that it is in a freshly precipitated state, in other words,

that the action of the lead sulphide in this statev somewhat corresponds to the action of gases in the nascent state. 'I'he particular manner in which the lead sulphide is formed, however, is not an essential step in the process as it may be precipitated in various ways such as by intro' ducing soluble lead salts and soluble sulphides .in the lactoilavin solution which react to form an insoluble lead sulphide precipitate as is well known in the art. A

From the foregoing descriptionit will be apparent that I have provided an improved process of preparing lactoiiavin by means of which high yields may be obtained. It will also be seen that by my improved process 'lactoiiavin concentrates may be produced in an economical manner without introducing poisonous solvents. The con-v centrates may therefore be safely utilized either alone or may be introduced into foods and medicinal preparations. v

What I claim is:

1. The process of preparing lactoflavin concentrates vwhich comprises introducing a soluble lead salt in a solution containing lactoiiavin, passing hydrogeirsmphide through the solution to form a precipitate, filtering to provide a lter cake containing the adsorbed lactoiiavin, heating a suspension of the lter cake containing the adsorbed lactoflavin in a solvent for the lactoavin, removing' the filter cake from the solution, and evaporating at least a portion of the solvent to obtain the lactoiiavin concentrate.

2. 'I'he process of preparing lactoavin concentrates which comprises introducing a soluble lead salt in a solution containing lactoiiavin, passing hydrogen sulphide through the solution to precipitate lead sulphide, filtering the lead sulphide together with the adsorbed lactoflavin, treating the iilter cake with a hot solvent for the lactoflavin, removing the lter cake from the solution and then evaporating at least a portion of the solvent to provide a lactoavin concentrate.

3. The process of preparing lactoiiavin concentrates which comprises dissolving a soluble lead salt in a solution containing lactoflavin, passing hydrogen sulphide through the solution to precipitate lead sulphide which adsorbsthe lactoiavin, ltering the precipitate, suspending the lter cake in Water, heating the water to the boiling point, removing the suspended particles, and evaporating at least a portion oi the Water to provide a lactofiavin concentrate.

4. The process of preparing lactoavin concentrates which comprises dissolving a lead salt which is at least partially soluble in water in a solution containing lactoavin, passing hydrogen sulphide through the solution to precipitate lead sulphide which adsorbs the lactoavin, ltering the precipitate from the solution, suspending the filter cake in a nonpoisonous solvent for the lactoflavin, heating the nonpoisonous solvent to elute the lactoilavin, removing the suspended particles of lead sulphide, and then evaporating at least a portion of the solvent to provide a lactoavin concentrate.

5. The process of preparing lactoavin concentrates which comprises introducing a soluble lead salt in a solution containing lactoavin, passing hydrogen sulphide through the solution to form a lead sulphide precipitate which adsorbs the lactoiiavin, removing the precipitate from the solution and eluting it with a solvent for the lactoi'lavin, and then removing the lead sulphide .rom the solvent.`

6. The process of preparing lactoavin concen-` trates which comprises introducing a soluble lead salt in`a solution containing lactoavin, passing hydrogen sulphide through the solution to form a lead sulphide precipitate which adsorbs the lactoilavin, removing `the precipitate from the solution and eluting it with a hoil solvent for the lactoavin, and then removing the lead sulphide.

'7. The process of preparing lactoavin concentrates which comprises precipitating lead sulphide in a solution containing lactoflavin which serves to adsorb the lactoavin, separating the lead sulphide and the adsorbed lactoavin from the solution, eluting the lead sulphide with a solvent for the lactoavin, and then removing the lead sulphide from the solvent.

8. The process of preparing lactoavin concentrates which comprises precipitating lead sulphide-in a solution containing lactoflavln which serves to adsorb the lactoavin in its freshly precipitated state, separating the lead sulphide and vadsorbed lactoiiavin from the solution, eluting the lead sulphide with a hot solvent for the lacto'- havin, and then removing the lead sulphide from the solvent.

9. The process of preparing lactoi'lavin concen-l trates which comprises precipitating lead sul-l phide in a solution containing lactoavin which serves to adsorb the lactoiiavin, separating the vlead sulphide and adsorbed lactoavin from the solution, eluting the lead sulphide with a solvent ior the lactoavin, removing the lead sulphide from the solvent, and then evaporating at y least a portion of the solvent under conditions which prevent oxidation or irradiation of the riactoavin. i

10. The process of preparing lactoavin con. centrates which comprises precipitating lead sulphide in a solution containing lactoavin which serves to adsorb the lactoavin, separating the lead sulphide and adsorbed lactoiiavin from the solution, agitating the lead sulphide in ay solvent for the lactoiiavin in which the lead sulphide is insoluble, adding a lter aid, ltering the solution to remove the lter cake, and then evaporating at least a portion of the solvent to form the lactoflavin concentrate.

HOWARD F. 

